Electronic device



F. M. PENNING ELECTRONIC DEVICE Filed Jan. 7, 1938 Aug. 13, 1940.

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Patented Aug. 13, 1940 vArea ELECTRONIC DEVICE Frans Michel Penning,Eindhoven, Netherlands, assignor, by mesne assignments, to Hartford 1National Bank andr'lfrust Company, Hartford,

Conn, as trustee Application January 7, 1938, Serial No. 183,893 In theNetherlands January 23, 1937 2 Claims.

ii) which contains, for example, heavy hydrogen,

lithium and the like, neutrons can be produced during the resultingnucleus reactionrI-Iereinafter the material against which the ions areprojected will be referred to as a disc of impact.

ii Such devices are also useful for effecting other nucleus reactions.For instance, they may be used to produce c particles by bombardment ofa lithium compound with hydrogen ions (protons), according to thereaction H +Li +2He or according to the reaction H +Li 2He In thelast-mentioned case lithium is consequently bombarded with ions of heavyhydrogen (deutons).

To produce neutrons in the above manner, de-

vices are known in which a stream of ions of heavy hydrogen produced ina glow discharge space is passed into a second space of the device inwhich the pressure is lower than in the glowdischarge space. The ionsare accelerated in the second space by applying a much higher potential,and-they finally strike a disc of impact containing, for instance, acompound of heavy hydrogen. Neutrons are produced due to meeting 'ofheavy hydrogen with a definite constituent of this compound, forinstance of heavy hydrogen or lithium, according to the nucleus re-'actions which are already known.

Although such prior-art; devices give satisfactory results, they havethe serious disadvantage, that it is necessary to maintain diiferentpressures in two communicating spaces, and for this purpose at least oneof these spaces must be continuously connected to a vacuum pump duringthe operation of the device.

5 The object of my invention is to overcome this disadvantage, and tosimplify devices of the above type.

The device according to the invention comprises an electric dischargetube having a plu- 5 rality of interconnected portions in which thepressure is the same. The ions are produced in a glow discharge takingplace in one portion and are accelerated in another portion, and strikefinally a disc of impact, which contains a definite v(i5 compoundto'produce the nucleus reaction. I

influence the glow discharge by a magnetic field,

. and give this magnetic field such a configuration,

and so shape the glow-discharge electrodes and so space the same withrespect to the magnetic field that the discharge current is muchstronger 5 than it would be were the magnetic field not present. By soarranging the magnetic field between the cathode and the anode that theelectrons emitted from the cathode must cover a much 10 longer path thanthat which they would cover without the magnetic field, the discharge'current is as strong as it would be without a magnetic field with amuch higher pressure of the gas. A second advantage of this arrangement5 is thefact that it is possible to strike the glow discharge whichwould be impossible Without a magnetic field.

This efiect of apparent pressure increase can be realized in variousmanners by means of the 20 magnetic field. According to one embodimentof'the invention the glow-discharge electrodes are shaped as fiat'platesarranged parallel to each other; and the magnetic field is so arrangedthat the magnetic lines of force extend perpen- .25 dicularly to theseplates. Thus not only an apparent pressureincrease is obtained duringoperation of the tube, butalso a. decrease in: ignition voltage which,of course, is also an important advantage. For example an apertured an-30 .ode may be arranged centrally between two cathodes, of which one isalso apertured for the passage of the ions produced.

In another embodiment the anode may be a cylinder or ring whose axisextends normally to 35 the surface of the cathodes and parallel to'themagnetic lines of force.

In the above cases the electrons move to and fro between the cathodesalong curved paths, and generally reach the anode only after having 40repeatedly moved back and forth. Consequently these paths areappreciably longer than the direct path from the cathode to the anode,and as a result the efiect produced is equivalent to an increase in thegas pressure. 5

In accordance with the variousapplications of a device according to thepresent invention, the gas in which the glow-discharge is. struck andthe substance bombarded by the ions produced are different. When thedevice is used for producing neutrons the glow discharge may be struckin heavy hydrogenand the ions produced may be projected against a discof impact containing heavy hydrogen or lithium in some compound orother; for example a compound of zirconium and heavy hydrogen.

' In order that the invention may be clearly understood and readilycarried into effect, I shall describe the same more fully with referenceto the accompanying drawing which is a sectionized view of a deviceaccording to the invention.

The discharge device illustrated in the drawing comprises an envelopehaving a vitreous portion I, two metal rings l and I8 for instance ofchrome iron, a connecting vitreous portion [9,-

and a vitreous portion 2. Portion which forms a glow-discharge chamber,is provided with a re,-'

entrant part forming a pinch 3 and two tubular projections 20 and 2|.Sealed in pinch 3 is a lead support 4 which carries on its lower end acathode 5 in the form of a'plate.

Beneath cathode 5 is an anode 1 in the form of a metal plate member, forinstance of constantan provided with a central aperture 8. Anode issupported at one side by a wire 22 sealed in the end of projection 20and onit's opposite side by a wire 23 sealed into the end of projection2| and extending therethrough to serve as a lead. Supported by wires 22and 23 are two vitreous cap-shaped members. 6 which extend over the endsof projections 20 and 2| and serve to protect wires 22 and 23"from'thedischarge.

Supported from ring I U is a second cathode 9 in the form of a metalcylinder, for instance of iron, whose ends are partly closed to formapertures 24 and 29. In a similar manner anaccelerating electrode llin'the form ofa metal cylinder, 'for instance of iron, having partlyclosed ends is supported from ring l8. I

Vitreous portion 2.forms a pinchll from which is supported a dis'c'ofimpact I2provided with a lead I3. The disc I2 may contain heavy hydrogen or lithium in'some compound for example a compound of'zirconiumand heavy hydrogen. Wherever throughout this specification the word"compound is used not only a chemical compound is meant but also a'bodywhich contains a gas absorbed'in it or adsorbed to it.

To prevent sparking over between rings Ill and I8, between which apotential difierence of for instance 60k. v. and more may beset u'pdur-' ing operation, the tube is supported by a plate l5 of suitableinsulating material such as Bakelite, and a suitable insulating cement16, such .as'pecine or similar material, is used to cover the surface ofportion [9 and to hold'the tube'to plate [5.

Surrounding the central portion of the'tube is a magnet coil" I! whichproduces in th'edischar'ge space a magnetic field whose lines of forceextend substantially normally't'o the surface of cathode 5 and anode I.v

To reduce the detrimental effect of secondary electrons merging from thedisc of impact [2; a

.resistance may be insertedin the supply lead I3.

As shown in the drawinga resistance 26 is connected between" lead l3 andthe high-tension source whereas the ring I8 is directly-connected tothis high-tensionsource.

Duringthe operation of the device the ions produced in theglow-discharge chamber pass through'apertures 24 and 29 and, after beingaccelerated by electrode ll,.. strike thedisc of impact l2 wherebyneutronsare produced.

a; particular example a voltage of about 15 k. v. may be appliedbetweencathodes 5 and 9 and anode I, a voltage of about 60 k. vQmay beapplied between cathode 9 and electrode II, and

resistance 26 may have a value of about 1 megohm. During operation thetube has a filling of heavy hydrogen at a pressure of about mm. Undersuch conditions coil 1 should produce a magnetic field having a value ofabout 800 gauss. The current may be of the order of magnitude of about 1ma. in the main discharge and of the order of 0.1 ma. in the disc ofimpact I2.

If the pressure of gas filling within the tube becomes too high or toolow due to the discharge, it may be readjusted in a known manner, forinstance by means of palladium tubes or by means of tubes of zirconiumwhich can absorb hydrogen as well as heavy hydrogen.

The pressure of the gas within a tube according to the invention may beadvantageously measured and supervised by means of the device describedin my copending U. S. patent application Ser. No. 106,915, filed October21, 1936, which device utilizes the fact that at a low pressure and byusing a suitable magnetic field, a glow discharge can be produced andthe intensity of the current of this discharge used as a measure of thepressure. This may, for instance, be effected by sealing to theextension 29 of the tube of Fig. 1, a separate tube in which a glowdischarge is struck at a low pressure in .a suitable magnetic field. Asmore fully described in the above application the magnetic field and theanode voltage of this separate tube are so selected that, for thepressure range used, the intensity of the glow discharge current isa'suitable measure of the value of the gas pressure.

While I have described my invention in connection with specific examplesand applications, I do not wish to be limited thereto but desire theappended claims to be construed as broadly as permissible in view of theprior art.

What I claim is:

1 A device for effecting nucleus reactions comprising an envelope, agaseous filling within said envelope, means within said envelope forproducing a glow discharge comprising a cathode having a plate-shapedportion, a second cathode having a plate-shaped portion provided with anaperture and arranged parallel to said first por ing a glow dischargecomprising a cathode having a plate-shaped portion, a second cathodehaving an apertured plate-shaped portion substantially parallel to saidfirst portion, and an anode consisting of an annular member arrangedwith its axis normal to said cathode portions, a disc of impactwithinsaid envelope,,means for accelerating the ions produced in thedischarge toward the disc of impact to effect a nucleus .reaction, andmeans to; produce a' magnetic field whose .lines of force extendsubstantially normal to .said cathode portions and parallel to the axisof the anode.

, FRANS MICHEL PENNTNG.

